Lenses and the aurora: Is Wide and Fast Necessary?

I zoomed in on the active portion of the display to get this image. I’ve never shot tight on the aurora before, but apparently it can work under the right circumstances. Canon 24-105 f4L @70mm, f4.0, 8sec, ISO3200.

Last night we had a good forecast for the aurora. I stayed up a bit beyond my normal bedtime to watch the alerts roll in and to check the local aurora web camera. About 10:30 or 11:00, the green haze that had been lingering to the north expanded and resolved into multiple curtains, so I grabbed my camera and tripod and stepped outside. As usual, my primary aurora lens, a 14mm f2.8 was on the camera, but as an afterthought, I pocketed my Canon 24-105 f4L. I wandered down to the open area on the lower portion of my property and stared northward, where absolutely nothing was happening.

I waited and thought that I could probably see a pale haze. I snapped a long exposure. The LCD showed me that yep, sure enough, there was some faint aurora. I waited. And waited. The cold wind blew and I tucked my nose into my parka and pulled up the hood. Then a single well-defined pillar of aurora appeared to the NW. I snapped a few images. The wide angle, showed just a starry sky and a small flash of green in the bottom of the frame. Boring. Then an arc of aurora appeared and I snapped a few more. The lights still insignificant in the wide-angle.

I’ve never before used the 24-105 for the aurora. It’s slower and less wide, and I couldn’t think of any time when I’d want a 105mm telephoto for shooting the northern lights. But out of curiosity, and to fend off rising boredom, I swapped out the 14mm for the 24-105.

The lights began to brighten and move south so I bumped my ISO from 1600 to 3200 (the fastest I generally feel comfortable on my 5D III) to compensate for the slower lens. The display was centralized low on the horizon to the NW. The rest of the sky was dominated by a pale arc of green, little of interest.

So, I zoomed. I shot from 40-105mm, concentrating on the active area of aurora. The lights were moving quickly and the 8 second exposure at f4 and ISO 3200 was still blurring the auroral movement so, I took a chance and bumped it all the way up to ISO 5000 and was able to get 4 sec exposures, just right to catch the pillars and curtains with some detail. But how much noise was this going to create?

I shot for another hour or so, finally growing too cold in the persistent wind. This morning I downloaded the images from the camera into Lightroom and got a look at how the 5DIII did at 5000 ISO. Turns out it, it did OK. The 5D has always been famous for its very low-noise images but I was amazed at how good these looked. Definitely some noise, but Lightroom was able to minimize it very well. Makes me wonder if I could go to 6400 or faster? Any photogs have experience shooting so high? I’d love to hear some thoughts.

But this did raise a question: Is the need for fast lenses a myth? With the low noise and high ISOs capable in today’s high end cameras, how much do we really need f1.2, 1.4, 1.8, or 2.8 lenses for night photography? Sure, if I’d been using an f2.8 I could have gone even faster, taking my exposures down to the 2 second range, but would that have made a tangible difference in the final images? I’m not sure. As cameras produce better and better image quality at high ISOs, are we really going to continue to need fast and extremely expensive lenses? Sure, there are aesthetic uses for the compressed depth of field of fast lenses, and that isn’t going to change. But for most photographers and landscape and nature photographers in particular, we are usually looking for more depth of field, not less. If we can compensate for slower lenses merely by pushing the ISO another stop or two, without loss in image quality, why should we invest thousands in fast glass?

It’s not a rhetorical question. I’d love to hear some opinions.

Canon 24-105 f4L @ 67mm, f4.0, 4 sec, ISO 5000

Canon 24-105 f4L @105mm, f4.0, 8 sec, ISO 3200. (Note the blurring in the aurora to the speed of the light’s movement and the 8sec shutter speed).

Canon 24-105 f4L @105mm, f4.0, 8sec, ISO 3200.

Canon 24-105 f4L, @40mm, f4.0, 10sec, ISO 3200. The aurora was very dim when I made this image. Check out the almost yellow color near the horizon, I haven’t seen that before.

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